Building this launcher is simple if you already have a mill. It does a remarkable job of pressurizing and launching soda bottles which are partially filled with water. The main component of this is a triple-gasket stopper with a quick release.

The problem with a lot of these water bottle rocket projects is that they leak where the bottle meets the launcher. In most cases this is a good thing as it’s almost impossible to build up enough pressure to cause the bottle to fail. This system has no such built-in safety mechanism, which is why the test launch below is conducted from a safe distance. After seating the partially filled bottle on the launch platform it’s pressurized to around 100 PSI at which point a yank on the string lets it fly.

Most of the time we look on these as casual projects. But we figure this one is much more suited for a rocket club or hackerspace event.

100psi? Nothing. We used to take fizzy drink bottles up to 10-15 bar before they exploded in our face. Upon reflection, only using a 3 foot tube on a bicycle track pump was probably not a good idea. The amazing thing is, when they blow up, we never found anything. No plastic shards, no label, nothing.
Sometimes we’d half fill with water and pull the connection off, the water would often freeze solid in the nozzle as it sprayed around wildly.

3 megapascal?!! THAT’s nothing. When I was a kid, we used to hook our 5cent plastic bottles up to the CERN particle collider, and turn it to the HI setting (just above the knob setting that read OOPS). Needless to say, there are two team of astro-physicists that are still trying to determine which planet our bottle landed on.

Me and my brothers used to blow bottles up with aluminum foil and some sort of heavy duty cleaner. The thicker ones would sound like a gun going off. Even had the local law enforcement come by a few times. surprisingly they never told us to stop. Always left with a laugh after seeing the cause of the noise demonstrated. One time a bottle was standing with the mouth down and blew the cap off. It was nearly 30 seconds before the bottle hit the ground.

Use muriatic acid and and aluminum foil wrapped in tubes the length of your finger about 3 sheets thick… Cap on to blow up the bottle. I bet if you created a nozzle to funnel the hydrogen through you could creat thrust. The nozzle would be sealed with a membrane that would blow just before anything else in the system failed. At this point a nose cone and fins could direct flight.

Sometime back there was fear mongering email forward making the round that had an element of truth, but misleading enough for me to consider it a hoax. Because as kid I’d use aluminum foil & lye in a pop bottle to fill kids balloon with hydrogen so they would float off. While doing this with a closed bottle ultimately would be dangerous it’s nearly impossible to target a victim with it as the email suggested.

this is what i do for work… i design the test gauges for cans/bottles. The standard 2L Bottle we are filling up to about 800PSI before first failure, but it will still hold a seal and pressure up to the 3rd failure at about 1400psi. i prefer aresol cans thoe… 3000psi to first failure, but that failure causes loss of pressure.

I actually made the launcher for a IBM event. Had a company picnick and they wanted to launch rockets for entertainment. I think there is still one rocket up in a tree. Few over engineered designs but everyone had fun and no injuries.

Pretty nice. Only one o-ring gland is required. Likely the need for 3 is due to the one sided release causing the bottle to cock slightly. A while back I modified my launcher to do some hydrostatic testing of the bottles. Most failed between 205 and 210 psi. Of course I couldn’t resist the temptation of doing some air filled tests. Started out by filling with the air compressor to 150 psi and then finish off with the hydraulic pump. You can read more here: http://weldingweb.com/showthread.php?t=88041